Recently i realized that if you have multiple images on your page and use Facebook comments or Facebook like then facebook creates wrong thumbnail in your wall. This happens because Facebook checks for first image or featured image in your page and if you have lots of images (even some thumbs) it considers them and creates thumbnail randomly unless you specifically mention which image to pic for thumbnail purposes.
I have also noticed that many sharing plugins also failing to fix the issue so i dug deeper and figure the solution out. Basically if you have multiple images on your page then it becomes vital to specifically mention which image should be used for thumbnail purposes in your header.
<link rel="image_src" href="http://site.com/original_image.jpg" />
you should use this on your page header or anywhere in your page to and then finally use Facebook Linter tool to test if the image and other related information is getting parsed correctly or not.
This is just a simple solution to solve the Facebook wrong thumbnail issue and i am damn sure that someone will come up even simpler option in sometime. This fix will also work for most of the sites which requires share preview features.
Please leave me a comment and let me know if you face any problems.